Production of color correction masks in multilayer photographs



Aug. 5, lsz G B, HARRlsQN ,gl-AL 2,606,116

PRODUCTION OF COLOR CORRECTION MSKS IN MULTILYER PHOTOGRAPHS Filed March 1'), 195o v 2 sHEE'rs-sm-:T 1

EXAMPLE 'I Mm? (a) v l murio ro MRM .mm/af (sn-p4).

ATTORNEYS Aug. 5, 1952 G. B. HARRISON ETAL 2,606,116

PRODUCTION OF COLOR CORRECTION MASKS IN MULQILAYER PHOTOORAPHS Filed March 17. 1950 2 SHEETS-SHEET 2 J n n l l :gtr/$55460@ our SILYE'R ATroRNEYs Patented Aug. 5, i952 PRODUCTION OF COLOR CORRECTION MASKS IN MULTILAYER PHOTOGRAPHS Georey Bond Harrison and Richard Robert Robinson, Ilford, England, assignors to Ilford Limited, llford, England, a British company Application March 17, 195o, serial No, 150,340 In Great Britain March 23, 1949 6 Claims.

1 This invention relates to colour photography and particularly to methods and materials for obtaining corrected colour images.

Most of the modern processes of colour photography are based on the use of an integral tri-'.1

pack material of the following general type: The material comprises a support and, superimposed on one side of the support, three silver halide emulsion layers, one of which is sensitised for the red region of the spectrum, one is sensitised for the green region of the spectrum, and the other. is not specially sensitised. Silver halide emulsion layers are normally sensitive to blue, and accordingly it is arranged that the notspecially-sensitlsed emulsion, which is sensitive to blue, is an outer layer of the three-emulsion layer assembly and there is provided a blueabsorbing layer between it and the remaining emulsion layers. Thus, when the material is exposed to a coloured object the blue, green and red records are recorded in their appropriate layers. Such a photographie multilayer material is hereinafter referred to as a material of the type defined.

For the sake of brevity the not-specially-sensitised emulsion will hereinafter be referred to as the blue-sensitive emulsion since it is in fact the only emulsion which is allowed torrecord the blue light received from the subject photographed. It will further be understood that in speaking of the blue-sensitive emulsion as an outer layer. it is meant that the blue-sensitive layer is not located between the other two layers; it may be closest to the support or the most remote from the support, but should in either case be the layer on which the light of the exposure is first incident.

When a material of the type described above contains colour-formers, and is subjected to colour A development, coloured images are formed in situ with the silver images. Colourformers are compounds which combine with the oxidation products formed during development by means of an aromatic primary amino developing agent, to form azomethine or quinoneimine dyestuff images in situ with the developed silver images, and colour development is the lterm applied to the production of such dyestui images.

By including in the emulsion layers colourformers which yield dyes which are complementary to the sensitivity of the layers, i. e. a colour-,former yielding a yellow dye in the bluesensitive layer, a colour-former yielding a magenta dye in the green-sensitive layer, and a colour-former yielding a cyan dye in the redsensitive layer, it is possible, by a reversal technique, tolobtain a positive icolour transparency in full colour. In an 'alternative technique the original material may be processed to a negative, i. e. containing negative colour images, and this may be copied onfto another multilayer photographic material, which in turn may be developed :to a positive: in this negative-positive technique the colour-farmers present in the layers ,of the materials need not be such as will yield dyescomplementary in colour to the sensitivities of vthe emulsions (as is broadly essential in thereversal technique), but providing the dyes are respectively subtractive to the primaries they may be generated in any of the emulsion layers, the correction being leffected by an appropriate choice of colour sensitivity and colour-former assembly in making the positive print. Such processes are referred to as false-colour processes and in further explanation of lthe technique, attention is drawn to British Patents Nos. 475,784y and Though processes such as those described above could theoretically yield` excellent results, difficulties arise in practice from several sources.' A principal source of difliculty is that it is jimpossible to nd three colour-formers which will yield ideally perfect dye images. There is always some departure from perfection and it is usually that the dye absorbs light of wavelengths which it should, ideally, freely transmit. Cyan dyes are generally the Worst, absorbing quite appreciably in the blue and green, while magenta dyes generally absorb too much in the blue. One result of this is that when a print is made from a negative coloured original, the colours of the printed image tend to be desaturated. The present invention is concerned with a method whereby the saturation of the colours obtained in the positive colour record, when using the negative-positive technique described above, may be improved.

According to the present invention a process for the production of a colour negative record from which improved colour positive copies may be obtained comprises exposing a multilayer material of the type defined and which contains colour-farmers in the emulsion layers, colourdeveloping the resultant latent images, converting at least part of the residual silver halide images to silver sulphide, and thereafter remov- -ing the negative silver images and any residual silver halide from the material.

The material thus obtained contains negative images in colour and complementary positive images in silver sulphide. The latter are brown or black in colour and form a so-called contrast mask so that when positive prints are made from the negative material colours of improved saturation are obtained in the prints.

It is preferred that aftery the rst development ofthe colour images the film, without further exposure, be treated in a vigorously acting developer of the metol-hydroquinone type in order to ensure that all the exposed silver halide is fully developed to silver.

The conversion of silver halide to silver sulphide may be allowed to take place in all the emulsion layers or may be confined to any particular layer or layers. Thus where in any layer the residual silver halide is not required to be converted to silver sulphide, the residual silver halide in that layer may be selectively exposed and developed to silver in a non-colour-forming developer, prior to the conversion treatment.

The selective exposuremay be eiected by using lightto which the particular layer only is sensitive, or by confining the exposure .to a particular layer by means of Y'a filter layer present in the A material..

The conditions of the treatment for converting residualA silverhalide to silver sulphide may be adjusted so that all of only part of the residual -sllverv halide is so converted. Conversion occurs imagewise, i. e. in dependence onthe amount of residual silver halide, and generally it is desirable that only part of the residual silver halide be so converted since full conversion tends to produce positive silver sulphide images of too high avcontrast. Thus, the contrast of the masking Vimage in any layer may bereduced by fully Vre-exposing the residual silver halide in that 'layer andA incompletely developing in a noncolour-forming developerfr a controlled time ,posing the.` residual silver halide in that layer and, developing to completion in a non-colourforming developer, Vthe re-exposure being con- `t1;(';l1f,:ds,o that only suflicient silver halide4 remains to provide apositive image of correct contrast after conversion to silver sulphide.

A combination of these two methods may be Yemployedfif preferred, and the methods may be selectively applied to produce separate masking images of the required contrast in the three emulsion, layers.

The conversion of silver halide to silver sulphidev may be effected quite Simply by bathing the material in a solutionv of a soluble sulphide, e. g. sodium sulphide.

The following examples will serve to illustrateA the invention :r

Example 1 A multilayer photographic material consisting of the following layers .was'prepa-red:

(a)l Transparent film support.

(b) Red-sensitive gelatino silver halide emulsion containing the sensitising dye described in Example`11 of British Patent No. 544,645, and

thoylamido-Z-methyl4 stearylaminofbenzene-isulphonic acid.

l(c) Green-sensitive gelatino silver halide emulsion containing the sensitising dye 3.39

G. Sodium carbonate (decahydrate) Sodium sulphite 6 Potassium bromide 2 Diethyl-p-phenylene diamine 2 Water to 1 litre.

(2) Developed for 5 minutes at 65 F. in a vigorous developer of the following composition to reduce residual exposed but undeveloped silver halide:

G. Metol .2 Sodium sulphite 75 Hydroquinone 8 Sodium carbonate (decahydrate) Potassium bromide 2 Water to 3 litres.

(3) Washed.

(4) Immersed in a 1% by weight aqueous solution of sodium sulphide for 21/2 minutes at 65 F.

(5) Washed.

(6) Bleached by treatment at 65 F. in a bath consisting of:

G. Potassium ferricyanide 100 Potassium bromide 50 Water to 1 litre.

(7) Fixed in 40% by weight aqueous sodium thiosulphate.

(8) Washed.

(9) Dried.

The product thus obtained was suitable for the production of colour prints of good saturation, the silver sulphide formed by step 4 acting as a positive contrast mask. This technique is illustrated in Figure 1 of the accompanying drawings, Figure 3 identifying the various legends employed in Figure 1.

It may be desirable to use a printing material which has a higher contrast than would be required to give a comparable print from a negative material processed without the formation of a masking image (e. g. by omitting steps 4 and 5). Alternatively, the dye images of the negative material may be processed to a higher contrast than would be employed were no masking image formed therein.

The foregoing example may usefully be modied where the yellow colour-coupler has very low red and green absorptions by introducing after step 1 the step of uniformly exposing the material by blue light incident on layer e. The lter layer d restricts the action of this light to the residual silver halide in layer e. Step 2 thus has the additional effect of converting the residual silver halide of layer e into metallic silver. N0 other modification being made in the procedure, the product obtained has silver sulphide positive contrast masks in layers b and c only.

Example 2 upper blue-sensitive layer, the material may be immersed in a dilute solution of sodium thiosulphate for a controlled time in order to allow partial xation of the residual silver halide. The remaining silver halide, chiefly in the lower layers, is then converted to silver sulphide as follows, the same material as was used in Example 1 being employed:

(l) Colourdeveloped for 12 minutes at 65 F. in a solution of the composition set out in Example 1, step 1.

(2) Rinse and immerse hardening bath. y

(3) Wash 5 minutes.

(4) As Example 1, step 2.

(5) Wash for 15 minutes.

(6) Partially fix by treatment in 5% sodium thiosulphate for 3 minutes.

(7') Rinse and then bathe in 1% sodium sulphide for 8 minutes.

(8) WashlO minutes.

(9) Bleach silver in a solution containing 10% potassium ferricyanide and 5% potassium bromide for 5 minutes.

V(l) Wash 5 minutes.

(11) Fix in plain 20% sodium minutes.

' (12) Wash 15 minutes and dry.

for l minute in an acid thiosulphate for Example 3 A masking image of silver sulphide which is v Gf. Sodium carbonate (decahydrate) 5() Thiourea 15 Water to 1 litre.

(7) Wash 10 minutes.

(8) Bleach silver in a solution containing 10% potassium ferricyanide and 5% l'potassium bromide, for 5 minutes.

(9) Wash 5 minutes.

(10) Fix in plain 20% sodium thiosulphate for 5 minutes.

(11) Wash 15 minutes and dry.

Example 4 A masking image of silver sulphide may be formed'substantially in the green-sensitive magenta dye image layer only by fully re-exposing the blue-sensitive and red-sensitive layers only before the black and white developmentwhich follows colour development. Residual silver halide is then present only in the green-sensitive layer for conversion to a mask.

The same material as was used in Example i is processed as follows:

v(1) As Example 2, step 1.

(2) Rinse and immerse for-1 minute in an acid hardening bath.

(3) Wash for 5 minutes.

(4) a. Re-expose the top blue-sensitive emulsion layer to blue light, e. g. by a 15 watt tungsten lament bulb behind Ilford lter 601. The word "1lford is a registered trade-mark. The intensity of exposure must be controlled to be sufiicient to re-expose the top layer without penetration of the filter layer and exposure of the "under layers.

b. Expose the nlm base surface to red light in order completely to re-expose the red-sensitive emulsion layer only, e. g. by a 15 watt tungsten lament bulb behind Ilford? lter 205.

(5) As Example 1, step 2.

(6) Wash 15 minutes.

(7) Bathe for 1 minute in a 0.1% solution'of sodium sulphide.

(8) to (12) Identical with steps 8 to 12 of Example 2.

The foregoing technique is illustrated in Figure 2 of the accompanying drawings, Figure 3 identifying the Various legends employed in Figure 2.

If desired the images in silver sulphide may be toned to other colours. Thus, for example, they may be converted to cadmium, arsenic or antimony sulphide by the general technique described in U. S. Patent No. 2,335,972.

The following example illustrates this modified procedure:

Example 5 Cadmium nitrate 30 Sodium cyanide 7() Water to l litre.

The material is finally washed and dried. When used for printing, the contrast of the image in the blue-sensitive layer of the positive material will have to be raised in order to compensate for the flattening of the yellow image in the negative by the mask.

What we claim is:

LA process orthe production of a colour record from which improved colour copies of opposite sense may be obtained which comprises exposing to a coloured subject a multilayer photographic element comprising a support end, superimposed on the support, three silver halide emulsion layers, one of which is sensitised for the red region of the spectrum, one is sensitised for the green region of the spectrum and one is sensitive only to the blue region of the spectrum, a blueabsorbing filter layer being located between the blue-sensitive emulsion layer and the other emulsion layers, each of said emulsion layers containing a colour-former, one of which yields on co1- our development a yellow dye, one of which yields on colour development a magenta dye `and one of which yields on colour development a cyan dye, colour developing the latent images formed by the exposure, re-exposing the element so that at least part oi the residual silver halide in at least one of the emulsion layers remains unaffected, developing the element in a non-colourforming developer, converting to silver sulphide at least part of the residual silver halide and thereafter removing silver and silver halide from the element, the colouration of the blue-absorbing filter being removed at any stage in the process.

2. A process for the production of a colour record from which improved colour copies of opposite sense may be obtained which comprises exposing to a coloured subject a multilayer photographic element comprising a support and, superimposed on the support, three silver halide emulsion layers, one of which is sensitised for the red region of the spectrum, one is sensitised for the green region of the spectrum and one is sensitive onlyvto the blue region of the spectrum, a blue-absorbing filter layer being located between the blue-sensitive emulsion layer and the other emulsion layers, each of said emulsion layers containing a colour-former, one of which yields on colour development a yellow dye, one of which yields on colour development a magenta dye and one of which yields on colour development'a cyan dye, colour developing the latent images formed by the exposure, re-exposing the residual silver halide in at least one of the emulsion layers, developing part only of such reexposed silver halide in a non-colour-forming developer, converting to silver sulphide the residual silver halide in at least the layers so reexposed and developed, and thereafter removing silver and silver halide from the element, the colouration of the blue-absorbing lter being removed at any stage in the process.

3. A process for the production of a colour record from which improved colour copies of opposite sense may be obtained which comprises exposing to a coloured subject a multilayer photographic element comprising a support and,

superimposed on the support, three silver halide emulsion layers, one of which is sensitised for the red region of the spectrum, one is sensitised for the green region of the spectrum and one is sensitive only to the blue region of the spectrum, a blue-absorbing filter layer being located between the blue-sensitive emulsion layer and the other emulsion layers, each of said emulsion layers containing a colour-former, one of which yields on colour development a yellow dye, one of which yields on colour development a magenta dye and one of which yields on colour development a cyan dye, colour developing the latent images formed by the exposure, fully re-exposing the residual silver halide in the emulsion layer containing the said colour-former which yields on development a yellow dye, at most partially re-exposing the residual silver halide in at least one of the other layers, developing the element in a non-colour-forming developer, converting to silver sulphide at least part of the residual silver halide, and thereafter removing silver and silver halide from the the element, the colouration of the blue-absorbing filter layer being removed at any stage of the process.

4. A process for the production of a colour record from which improved colour copies of opposite sense may be obtained which comprises exposing to a coloured subject a multilayer photographic element comprising a support and, superimposed on the support, three silver halide emulsion layers, one of which is sensitised for the red region of the spectrum, one is sensitised for the green region of the spectrum and one is sensitive only to the blue region of the spectrum, a blue-absorbing nlter layer being located between the blue-sensitive emulsion layer and the other emulsion layers, each of said emulsion layers containing a colour-former, one of which yields on colour development a yellow dye, one of which yields on colour development a magenta dye and one of which yields on colour development a cyan dye, colour developing the latent images formed by the exposure, exposing to light the residual silver halide in at most two of the emulsion layers, developing the element in a noncolour-forming developer, converting at least part of the residual silver halide in the remaining emulsion layers to silver sulphide by treating the element with a soluble sulphide, and thereafter removing silver and any residual silver halide from the element, the colouration of the blue-absorbing filter layer being removed at any stage of the process.

5. A process for the'production of a. colour record from which improved colour copies of opposite sense may be obtained which comprises exposing to a coloured subject a multilayer photographic element comprising a support and, superimposed on the support, three silver halide emulsion layers, one of which is sensitised for the red region of the spectrum, one is sensitised for the green region of the spectrum, and one is sensitive only to the blue region of the spectrum, a blue-absorbing lter layer being located between the blue-sensitive emulsion layer and the other emulsion layers, each of said emulsion layers containing a colour-former, one of which yields on colour development a yellow dye, one of which yields on colour development a magenta dye and one of which yields cn colour development a cyan dye, colour developing the latent images formed by the exposure, re-exposing the element so that at least part of the residual silver halide in at least one of the layers remains unaffected, developing the element in a non-colourforming developer, converting to silver sulphide at least part of the residual silver halide by treating the element with a soluble sulphide, and thereafter removing silver and silver halide from the element, the colouration of the blue-absorbing filter layer being removed at any stage of the process, and nally converting the silver sulphide formed to another metal sulphide by ion-interchange with a salt of said other metal.

6. A process for the production of a colour record from which improved colour copies of opposite sense may be obtained which comprises exposing to a coloured subject a multilayer photographic element comprising a support and, superimposed on the support, three silver halide emulsion layers, one of which is sensitised for the red region of the spectrum, one is sensitised for the green region of the spectrum, and one is sensitive only to the blue region of the spectrum. a blue-absorbing lter layer being located between the blue-sensitive emulsion layer and the other emulsion layers, each of said emulsion layers containing a colour-former, one of which yields on colour development a yellow dye, one of which yields on colour development a magenta dye and one of which yields on colour development a cyan dye, colour developing the latent images formed by the exposure, re-exposing the element so that at least part of the residual silver halide in at least one of the layers remains unaffected, developing the element in a non-colourforming developer, converting to silver sulphite at least part of the residual silver halide by treating the element with a soluble sulphide, and thereafter removing silver and silver halide from ing filter layer being removed at any stage of the the element. the colouraton of the blue-absorbprocess, and finally converting the silver sulphide formed to cadmium sulphide by treatment with a solution containing a soluble cadmium salt and a cyanide.

GEOFF'REY BOND HARRISON.

RICHARD ROBERT ROBINSON.

REFERENCES CITED The following references are of record in the 111e of this patent:

Number 2,143,737 2,203,653 2,431,996 2,476,541

Number 10 UNITED STATES PATENTS Name Date Mannes et al Jan. 10, 1939 Evans June 4, 1940 Duerr et al. Dec. 2, 1947 Friedman July 19, 1949 FOREIGN PATENTS Country Date Great Britain Jan. 18, 1940 

1. A PROCESS FOR THE PRODUCTION OF A COLOUR RECORD FROM WHICH IMPROVED COLOUR COPIES OF OPPOSITE SENSE MAY BE OBTAINED WHICH COMPRISES EXPOSING TO A COLOURED SUBJECT A MULTILAYER PHOTOGRAPHIIC ELEMENT COMPRISING A SUPPORT END, SUPERIMPOSED ON THE SUPPORT, THREE SILVER HAILED EMULSION LAYERS, ONE OF WHICH IS SENSITISED FOR THE RED REGION OF THE SPECTRUM ONE IS SENSITISED FOR THE GREEN REGION OF THE SPECTRUM AND ONE IS SENSITIVE ONLY TO THE BLUE REGION OF THE SPECTRUM, A BLUEABSORBING FILTER LAYER BEING LOCATED BETWEEN THE BLUE-SENSTIVE EMULSION LAYER AND THE OTHER EMULSION LAYERS, EACH OF SAID EMULSION LAYERS CONTAIN ING A COLOUR-FORMER, ONE OF WHICH YIELDS ON COLOUR DEVELOPMENT A YELLOW DYE, ONE OF WHICH YIELDS ON COLOUR DEVELOPMENT A MAGENTA DYE AND ONE OF WHICH YIELDS ON COLOUR DEVELOPMENT A CYAN DYE COLOUR DEVELOPMENT THE LATENT IMAGES FORMED BY THE EXPOSURE, RE-EXPOSING THE ELEMENT SO THAT AT LEAST PART OF THE RESIDUAL SILVER HALIDE IN AT LEAST ONE OF THE EMULSION LAYERS REMAINS UNAFFECTED, DEVELOPEING THE ELEMENT IN A NON COLOURFORMING DEVELOPER, CONVERTING TO SILVER SULPHIDE AT LEAST PART OF THE RESIDUALL SILVER HALIDE AND THEREAFTER REMOVING SILVER AND SILVER HALIDE FROM THE ELEMENT, THE COLOURATIN OF THE BLUE-ABSORBING FILTER BEING REMOVED AT ANY STAGE IN THE PROCESS. 